only allow installing packages on the root volume (custom locations wouldn't work anyway), see https://trac.macports.org/ticket/14809
only allow installing packages on the root volume (custom locations wouldn't work anyway), see https://trac.macports.org/ticket/14809

git-svn-id: 620571fa9b4bd0cbce9a0cf901e91ef896adbf27@53250 d073be05-634f-4543-b044-5fe20cf6d1d6

danchr/macports-base,macports/macports-base,neverpanic/macports-base,danchr/macports-base,neverpanic/macports-base,macports/macports-base